I've read terrible things about the South African rust. I heard the German rust is much flakier and contributes to total structural failure a lot quicker. A better quality rust all round really. BMW shouldn't open these overseas plants unless they can absolutely guarantee OEM quality.

i think best solution is email BMWNA as someone noted above.
They've contacted me back, I gave them VIN and other info - let's see what they do. I think they're noting it and it'll be taken care of.
So annoyed...underimpressed with QC on these new cars.

i talked to BMW NA customer care on the phone today and they made a note for my vin number. i told them its basically on every car and im sure they'll be hearing from more people but the guy said they didn't have a notice and he hadnt heard of it yet over there.

BMW Canada called me back today after discussing it with the dealer I brought it to. They asked me to setup another appointment with the dealer where they can take pictures of the rust and send it off to HQ. It's better than doing nothing and pretending everything's normal. Let's see what their response is.

BMW Canada called me back today after discussing it with the dealer I brought it to. They asked me to setup another appointment with the dealer where they can take pictures of the rust and send it off to HQ. It's better than doing nothing and pretending everything's normal. Let's see what their response is.

Here are a couple pics of the underside of the seats. Might not be anything but I wanted to throw this out there. Any thoughts?

Throughout this thread, I think we might be looking at two types of chemical residues. I'll refer to them as Type A
and Type B.

Type A : the yellowish residue shown in your E90-M3 photos (Post #85, page 3) is almost identical to what I found on the underside of my car's seats (F30-335i mid-October production). I believe this may well be a chemical residue left over from the galvanic production process, when the seat frames were supported by trays on the assembly line. You will note the mostly linear shape to the residue areas shown in your photos.

My dealer's service manager examined my seats today, and he agreed with my thoughts. He mentioned that he had already observed about 10 F30s with genuine signs of brownish-orange rust, both on the underside of the seat frames and on some of the seat hinges (see Type B below). My car's seat hinges are painted black; apparently, hinges in the early production cars were not painted. The cars with rust referred to by my service manager were from earlier production.

Type B : presented by the OP, Steve_Jr, (Post #1), where large, amorphous and random areas of brownish-orange oxidation, being typical of surface rust, were evident in the photos. If my seats presented Type B oxidation, I would most certainly request a replacement seat frame under warranty.

But I would caution anyone with the Type A residue to requesting a seat dis-assembly and frame replacement, if in fact BMW would even authorize such a claim. The potential cure may be worse than the apparently harmless cosmetic change to the underside of the seat frame. If a seat is dis-assembled, it will not likely be re-assembled in exactly the same way as it was originally at the factory. There are bound to be minor variations in the padding after re-assembly, in addition to potential rattles and squeaks that were not previously present.

This is on an F31 320d Sport. Build date 18th September. Less than 200 miles on the clock.

Wow, rustier than mine. You definitely need new seat frames with proper rust prevention e-coating.
You, or dealer, can clean up the rusts for now, but eventually the rust will come out again because the current metal frames didn't have rust prevention coatings.
Visible hinges will get worse too.

The car is actually on loan from BMW UK until my new one arrives in February. I'm loathe to start getting warranty work carried out on a car that isn't mine. However, I will be notifying the dealer. Once I'm done with it the car will probably end up on the AUC site. Pointing out the rust is the least I can do for the next keeper.

I scheduled a visit to my dealer next week to have them take a look at my 2 rusty seat frames. I also emailed BMWNA Customer Care to see how they'd respond. They just told me to go to the dealer. Not too encouraging.

FWIW, I also checked the warranty related to rust. If the seats are considered part of the 'body', coverage is 12 years. That's some consolation, anyway.

FWIW, I also checked the warranty related to rust. If the seats are considered part of the 'body', coverage is 12 years. That's some consolation, anyway.

More than likely the seats would be covered for the 4yr/50K warranty period. That said, I suspect when all is said and done, BMW will offer an extended warranty for the seat frames of affected vehicles. Like they did for the fuel pump issues in the N54 E90 cars.